The Paleozoic Huoshenmiao iron skarn deposit in the Tongbai area of North Qinling Orogen,China:Insights from garnet U-Pb dating and geological constraints  

作　　者：Mingchun CHAI Hao HU Jianwei LI Shiguang DU Linfeng HOU 

机构地区：[1]School of Earth Resources,China University of Geosciences,Wuhan,430074,China [2]State Key Laboratory of Geological Process and Mineral Resources,China University of Geosciences,Wuhan,430074,China [3]Pu’er Natural Resources and Planning Bureau,Pu’er,665000,China

出　　处：《Science China Earth Sciences》2021年第12期2172-2189,共18页中国科学（地球科学英文版）

基　　金：This work was supported by the National Natural Science Foundation of China(Grant No.41772081).

摘　　要：The Qinling Orogen is a composite orogenic belt that can be subdivided into the North and South Qinling,broadly separated by the Shangdan suture zone.These two orogenic belts were generated by subduction-collisional processes in the Early Paleozoic and Late Triassic,respectively.During the Late Jurassic to Early Cretaceous,the eastern portion of the Qinling Orogen was tectonically reactivated due to westerly subduction of the Izanagi plate underneath the East China continental margin.The Qinling Orogen is well-endowed with numerous Au,Mo,Ag-Pb-Zn deposits that predominantly formed in the Late Triassic to Early Cretaceous,with rare Paleozoic varieties documented.In this study,we present garnet and zircon U-Pb dating results to show that the Huoshenmiao iron skarn deposit in the Tongbai area of North Qinling orogenic belt formed in the Early Silurian and is genetically related to subduction-related magmatism.The Huoshenmiao deposit consists of lenticular and stratiform orebodies that contain massive or densely disseminated magnetite variably associated with garnet,diopside,epidote,hornblende,and actinolite.Garnets from iron ores are andradite and grossular in composition(Ad_(83.1)Gr_(13.3)-Ad_(86.5)Gr_(10.2))and characterized by enrichment in light rare earth elements(ΣLREE=57.85-103.82 ppm)and depletion in heavy rare earth elements(ΣHREE=5.50-11.34 ppm),with significantly positive Eu and Ce anomalies(δEu of 1.09-1.89 andδCe of 1.39-1.69).These compositional signatures are distinctly different from those of garnets in the ore-hosting metamorphic rocks that are typically dominated by almandine,spessartine and grossular(Al_(47.4)Sp_(30.4)Gr_(13.8)-Al_(51.9)Sp_(24.8)Gr_(17.6)),depleted in LREE(0.14-0.69 ppm),enriched in HREE(95.68-841.60 ppm)and have pronounced negative Eu anomalies(δEu=0.24-0.51).In addition,garnets from iron ores of the Huoshenmiao deposit contain abundant daughter mineral-bearing,multiphase fluid inclusions,further confirming their hydrothermal origin.Two samples of those hydrothermal garnets

关 键 词：Huoshenmiao iron skarn deposit Tongbai area North Qinling orogenic belt Paleozoic metallogeny 

分 类 号：P618.31[天文地球—矿床学]